There are a couple of things to notice here:
* firstly how Luke stresses the role of the Holy Spirit (or rather, God, since at the start it is "an angel of the Lord")
* it may have been a desert/wilderness road but like Abraham in Gen 12 "he got up and went" our response to such promptings is often more cautious, even at times Jonah-like
* the Ethiopian official was prepared (been to temple, so God-fearer, reading Scripture - measure of his importance he had a copy)
* Isaiah again!
Bible Jesus Read, The
Philip Yancey. Zondervan 2002, Paperback, 240 pages, $1.94
Like Yancey's friend (see Reading prophets for pleasure and profit
) he recognised what he was reading was difficult.
"Do you understand?" "How can I, unless someone guides me?"
The passage he was reading came from Is 53:7-8. Philip started with this scripture, and proclaimed to him the good news about Jesus. Christianity fits with, but goes beyond - fully fills - the Scripture that preceded it.